The present embodiments relate to a gantry for an X-ray device.
In radiation therapy and in many computed tomography systems, signals are transmitted from a stationary part to a rotatable part of a gantry using a contactless transmitter for example, by induction. As a result, spark development and high wear in such transmission types as wiper rings are avoided. German Patent DE 28 55 379 C2 discloses a contactless power transmission.
As shown in FIG. 2, a contactless power transmitter for power transmission includes a primary coil on the stationary part of the gantry, a secondary coil on the rotatable part of the gantry, and at least one transmitter core. A plurality of transmitters for different system components to be supplied with power may also be present on one gantry.
For structural reasons, an air gap between the stationary part and the rotatable part of the gantry is unavoidable. A magnetic stray field develops around the air gap. The size of the magnetic stray field is in proportion to its size. The magnetic stray field of a transmitter can enter into interaction with the magnetic stray field of a different transmitter, with capacitive coupling paths for data transmission, or with electronic system components. The result of the interaction with other magnetic stray fields can be mutual interference with transmission, to the point of damage to system components.
If there are two transmitters side by side, of which the first is responsible for supply to the X-ray tube and the second is responsible for voltage supply otherwise, the interaction at the X-ray tube, despite the first transmitter having been switched off, can permanently cause a voltage of up to several kV. This can lead to unwanted radiation generation.
The interaction may possibly be reduced by creating a sufficient distance from the stray fields or between the stray fields. For example, for an air gap of approximately 1 mm, to attain any improvement the distance between two inductive transmitters would have to be at least 10 cm, but for structural reasons that is often not possible.